topic 1 orgs Flashcards
(22 cards)
what is a population?
a population is a group of individuals of a species that occur together at the same place and time.
what are the 4 types of evidence that supports the theory of evolution by natural selection
- fossils
- the anatomical record
- genetic sequences
- selection experiments/ observations
what does the term vestigial mean?
organ or part of the body which has become functionless in the course of evolution
what are homologous structures?
homologous structures have a different appearance among species but derive from the same body part in a shared ancestor
what are the modes of selection (3)
directional selection
stabilising selection
disruptive selection
what are the sources of variation?
sexual recombination (genes from both parents)
mutation
gene flow (movement of organisms from one place to another.
how do species arise?
they arise through evolution
what is the difference between analogous traits and homologous traits?
homologous traits are traits that are shared between species, e.g the limbs of a human and cat are the same but have evolved in different ways
analogous traits are similar traits but are not related to each other eg flying in a bird compared to a moth, two different structures.
what does fitness refer to?
fitness refers to the combined effects of survival and reproduction on the growth of a population
what does natural selection do in terms of genes frequency?
natura selection effects the frequency of genes in a population through its effects on the survival and reproduction of individuals that have different genotypes
what is adaptation?
adaptation is an inherited characteristic of an organism that enhances its survival and reproduction in specific environments
it is a continuous process
what is genetic drift?
random changes in a gene frequency, important in small populations
what are the two steps of speciation ?
- the characteristics of initially identical populations must diverge
- reproductive isolation must evolve to maintain differences
eg a lake that dries up in the middle and one side the fish become blue and the other remain red.
what is alopatry?
populations occur in seperate locations with a barrier between them
what is sex?
the coming together of genetic material from two parents to form progeny that combines genes from both of them
what do females look for in males?
females choose based on male traits and signals that are indicators of fitness
what is runaway sexual selection
even if there are negative effects associated with the male trait, women will still select the males with the negative trait, eg peacocks with more spots get chosen by females more despite it being more prone to predation. This trait only stays if gains in reproduction out weigh losses in survival
what are archaea
ancient bacteria
single celled organisms that lack a nucleus
can inhabit extreme environments
what are bacteria
most abundant organisms on earth
simple single celled organisms that lack a nucleus
eukarya
the ancestral eukaryotic cell probably had a nuclues
mitochondria were acquires as a endosymbiotic photosynthetic bacteria
what are some characteristics of fungi
heterotrophic - obtain nutrients from the environment
fiamentous strucutres - bodies are up of hyphae
cell walls composed of chiting
store glycogen - not starch
thought to have evolved from an aquatic flagellum bearing single celled organism
what does symbiosis and mutualistic mean
symbiosis = living together
mutualistic = beneficial to both partners
